A loss of a secondary flow of air into a gas-path of a turbine has a negative effect on engine fuel bum, performance/efficiency, and component life. Metal w-seals or dog-bone seals are commonly used to limit leakage of secondary flow between segmented or full-hoop turbine components.
Exposure to significant relative axial/radial deflections, intermittent loading points, and/or elevated temperatures can preclude the use of w-seals or cause w-seals to deteriorate and be ineffective over time.
Dog-bone seals, unlike most w-seals, are full-hoop (i.e. not split in one circumferential location) and therefor require significant radial clearance to mating hardware that form the seal cavity. As a result, dog-bone seals cannot be kept concentric with an engine centerline and therefore cannot be kept in alignment with sealing features on mating hardware, such as feather seal slots.